Camouflage covering for protection against nuclear explosion



Wino-71.310

l United States Patent ice AGAINST NUCLEAR EXPLOSION Meyer I. Landsberg, Wayland, Abraham L. Lastnik, Framingham, and Jean L. Lewis, Worcester, Mass,

sented by the Secretary of the Army No Drawing. Filed Dec. 9, 1959, Ser. No. 858,555 13 Claims. (Cl. 4110) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein, if patented, may be manufactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

This invention relates to camouflage covering for protection against thermal radiation caused by a nuclear explosion, and more particularly to a two-ply covering; the inner plybeing a highly retlectant metallic sheet and superposed thereon an instantly combustible camouflage fabric ply.

A nuclear explosion results in three principal types of damage: blast damage, heat damage, and damage from ionizing radiation. Of these, the heat damage usually extends over a longer radius than the others, due to the tremendous heat radiated from the place of occurrence of the nuclear explosion. The thermal radiation travels in straight lines and obliterates or damages those objects in its path that are not shielded.

On the other hand, thermal radiation emanating from the source of the atomic explosion has little penetrating power, and at some distance from the locus of the explosion is capable of being reflected by a reflectant surface, such as bright metal. Thus, a person or object covered with a metallic sheet, metallized cloth, and the However, such a protection by a highly reflectant cover t has a serious and often decisive military disadvantage, in that the reflectant covering is visible at great distances by an observing enemy, who will then proceed to eliminate the military object by conventional means, such as artillery shelling or conventional aerial bombardment.

We have discovered that a covering which protects against thermal radiation as Well as against enemy observation can be simply and effectively provided by a twoply construction in which the inner ply is a highly reflectant metallic object, and the outer ply is an instantly combustible fabric of low reflectance. The metallic layer may be e.g., a sheet of aluminum, titanium, tear-resistant tinfoil, metallizcd cloth, and the like. The metallic layer, if exposed to thermal radiation, reflects about 80% thereof. The instantly combustible fabric outer ply is of low reflectance, and is of a solid or patterned camouflage color well known to the camouflage expert, e.g.,

-olive green in the temperate zone, khaki in the desert or patterned in shades of brown and green for jungle warfare. The fabric material is selected from instantly combustible materials without appreciable afterflaming, representative examples of which are: wool, silk, rayon (viscose), polyethylene terephthalate (Dacron), polyacrylonitrile (Orlon), acrylonitrile vinyl copolymer (Dy- 4 l t. i.

i i i I 3,059,364 Patented Oct. 23, 1962 ,2 and fabrics of mixtures of two or more of the foregoing textile fibers. Cotton, a non-proteinaceous substance (as contrasted with proteinaceous textiles such as wool, silk or zein fibers) has less favorable burning characteristics for the purposes of our invention, but may be made assignors to the United States of America as represuitable therefor by impregnation with a flame propagant, as will be more fully explained hereafter. Saponified cellulose acetate (Fortisan) fabric wasfound unsuitable because of its long aftcrllaming.

While it is customary in the provision of fabric material for ordinary military clothing, tarpaulinsand the like, to fiarneproof the fabric by a chemical treatment with a flame-resistant composition, such a practice is detrimental to the object of our invention. and to the contrary we obtain a more etlicient covering by treating the fabric with a flame-propagating composition so as to increase its flammability.

Thus, the combustion rate of a rayon fabric is matcrially increased by impregnation with a nitrate. such as ammonium nitrate. The llanunability of nylon is raised by impregnation with coppcr-8-quinoiinolate (a wellknown fungnaproofing agent), so as to deposit about. .01 to about .5% copper in the fabric.

The following table indicates a number of results obtainetl by testing a number of two-ply covers in accordance with our invention. The effectiveness was measured by determining the temperature rise behind .the cover, when subjected to a predetermined energy flux measured in calories per square centimeter per second, as delivered by a carbon arc. 5 I

Contrary to the expectation that the heat of combus tion of the fabric cover would decrease the protection afforded by the metal layer by reason of heat conduction through the metal layer, it was found surprisingly, how- 85 ever, that some of the tested fabric plies even increased the eiiiciency of the composite cover, as compared with the efficiency of a non-covered aluminum refiectant. It should be borne in mind that even in those instances where the efficiency of the two-ply cover system was about the same'o'r slightly less than that of the non-covered refiector, the loss is compensated, from the military standpoint, by the gain in camouflage characteristics.

As previously noted, untreated cotton showed relatively poor overall results due to its unfavorable burning characteristics; this can be overcome by a nitrate treatment.

Nylon showed a better overall performance=than cotton, but did not perform as well as the other materials tested. It was observed that nylon left a smoldering residue on the aluminum ply which caused the latter to 3 conduct heat to the interior. This disadvantage can be overcome by treating the nylon fabric with copper-8- quinohnolate. The following table shows the improved results obtained by such a treatment. 7

These results Show that the copper-8-quinolinolate improved the flammability characteristics of nylon to such an extent that up to 71% of the undesirable nylon melt is eliminated, with consequent improvement of the temperature rise results (9.4" C., as compared with 14.6 C. for untreated nylon).

In the case of proteinaceous outer plies (wool, silk, Vicara), it was observed that a hard brittle dome-like crust formed in the area exposed to the thermal radiation. This dome-like crust forms a captive gas space that acts as an insulator; the gas contents of the crust being the decomposition products of the protein, e.g., nitrogen. Even if the dome-like crust does not break and becomes a secondary emitter of thermal radiation, the reflective surface is still capable of functioning. If the crust breaks, the underlying metallic surface is fully eifective as a reflector.

In a modification of our invention, we have surfacetreated the fabric ply with an alcoholic solution of formaldehyde-modified nylon, and used it as an outer ply over the metallicply in accordance with our invention. Upon exposure to high energy thermal radiation, the outer ply formed a foamed coating, providing appreciable thermal insulation. Alcohol-soluble formaldehyde mOdified nylon is shown in US. Patent No. 2,430,860, Cairns.

An analogous effect was achieved by treating the outer fabric ply, e.g., nylon fabric, with a nitrogen-releasing blowing agent such as p,p'-oxy-bis-benzenesulfonyl-hydrazide, sold commercially under the trade name Celogen.

the two plies may either be secured together by edge fastening and the like, or the covering may be simply formed by draping the fabric ply over the metal ply.

It will thus be seen that we have provided a highly effective protective covering which serves to camouflage personnel or supplies against enemy observation and at;

, fords a high measure of protection against thermal radiation emanating from a nuclear explosion, provided the explosion does not occur at so close a range as to be within the effective radius of the blast effect. The principle of the protective effect of such a covering is the immediate burning off of the outer ply so as to either expbsc the reflectant surface of the inner ply or to provide the latter with a gas-containing protective crust of high thermal insulation quality, or a combination of both. a

While we have described various illustrative examples for carrying our invention into practice, itis evident that numerous modifications and adaptations. all within the spirit and scope of our invcntionuill readily occur to the expert. We intend to encompass any such variations within the scope of the appended claims by which we now proceed to define our invention.

We claim:

1. .Camouflage covering for protection against thermal radiation caused by a nuclear explosioh, essentially corisisting of a highly reflectant non-combustible sheet and superposed thereon a quickly combustible cellulosic fabric of low reflectance, said fabric being treated with a flame propagating agent, said flame-propagating agent being ammonium nitrate; whereby upon the occurrence of a nuclear explosion said superposed treated fabric is instantly burned oflf, and said thermal radiation is reflected by said highly reflectant non-combustible sheet.

2. Camouflage covering according to claim 1, wherein said cellulosic fabric is cotton.

3. Camouflage covering according to claim 1, wherein said cellulosic fabric is rayon.

V superposed thereon a quickly combustible fabric of a low This caused the formation of a captive gas space similar v tightly woven white glass fiber fabric may be used in lieu of the metallic sheet, the outer ply preferably being a flamc-propngant-treated fabric.

As stated, protective camouflage coverings constructed in accordance with our invention may be used to cover inanimate objects, e.g., stacks of ammunition, rations or other supplies, or may be used to provide covering for military personnel. If used for the protection of supplies, such coverings are advantageously in the form of a tarpaulin. If used as a personnel protectant, the covering may be in the form of a garment such as a poncho or hood. A tent made of protective covering in accordance with the present invention may be used for the protection of personnel, materiel or both. The physical construction of the foregoing and other types of covers is no reflectance, said fabric being treated with a nitrogen-rcleasing blowing agent; whereby upon the occurrence of a nuclear explosion said superposed fabric is instantly burned off, and a heat-insulating nitrogen-gas-containing crust cooperating with said highly reflectant non-combustible sheet is instantly formed. j f 6. Camouflage covering according to claim 5 wherein said fabric is nylon. j

7. Camouflage covering according to claim 5 wherein said nitrogen-releasing blowing agent is p,p'-oxy-bis-bcnzenesulfonyl-hydrazide.

8. Camouflage covering according to claim 6 wherein said nitrogen releasing blowing agent,is p,p'-oXy-bis-benzenesulfonyl-hydrazide.

9. Camouflage covering for protection against thermal radiation caused by a nuclear explosion, essentially con sisting of a highly reflectant non-combustible sheet and.

superposed thereon a quickly combustible fabric of low reflectance, said fabric being treated with a solution of alcohol-soluble formaldehyde-modified nylon; whereby upon the occurrence of a nuclear explosion the superposed fabric is instantly burned off, and a heat-insulating foam cooperating with said highly reflectant non-com- 10. Camouflage covering according to claim 1, wherein said non-combustible refiectant sheet is aluminum.

11. Camouflage covering according to claim 4, wherein said non-combustible refiectant sheet is aluminum.

12. Camouflage covering according to claim 5, wherein said non-combustible reflectant sheet is aluminum.

13. Camouflage covering according to claim 9, wherei in said non-combustible reflectant sheet is aluminum.

References Cited in the file of this patent UNITED STATES PATENTS 1,611,031 Henderson Dec. 14, 1926 v H 2,630,573 1 s r 2,656,295

Reynolds Sept. 1, 1959 

1. CAMOUFLAGE COVERING FOR PROTECTION AGAINST THERMAL RADIATION CAUSED BY A NUCLEAR EXPLOSION, ESSENTIALLY CONSISTING OF A HIGHLY REFLECTANT NON-COMBUSTIBLE SHEET AND SUPERPOSED THEREON A QUICKLY COMBUSTIBLE CELLULOSIC FABRIC OF LOW REFLECTANCE, SAID FABRIC BEING TREATED WITH A FLAME PROPAGATING AGENT, SAID FLAME-PROGAGATING AGENT BEING AMMONIUM NITRATE; WHEREBY UPON THE OCCURRENCE OF A NUCLEAR EXPLOSION SAID SUPERPOSED TREATED FABRIC IS INSTANTLY BURNED OFF, AND SAID THERMAL RADIATION IS REFLECTED BY SAID HIGHLY REFLECTANT NON-COMBUSTIBLE SHEET. 